The present invention relates to assemblies of solder-bearing terminal elements or leads and electrical components for assembly with printed circuit boards or other substrates, and to methods of fabricating such terminal elements or leads and attaching them to electrical components.
In the electronic equipment industry, an important necessity is the rapid and accurate assembly of electrical circuit components such as resistors, capacitors, integrated circuit chips, and chip carriers with printed circuit boards or other substrates. For connecting such components to substrates, leads are necessary. It has previously been suggested to facilitate the connection of such leads to components or to substrates by securing a solder slug or mass to the lead. When positioned in engagement with a circuit board and heated, the molten solder will cover the adjacent surfaces of both elements to form, when cooled, a soldered joint providing both a mechanical coupling and an electrical connection between the elements. Various exemplary arrangements of arrays of leads with solder-holding elements for automated assembly are disclosed in Seidler U.S. Pat. Nos. 4,120,558, 4,203,648, 4,679,889, 4,728,305, and 4,780,098, which patents are hereby incorporated by reference. The last three patents are specifically directed to solder-holding leads that allow for very close spacing of the leads from which they are formed.
To attain greater miniaturization in this field, size of and spacing between conductive terminals for surface-mounting electrical components on printed circuit boards, for example, have been reduced. Thus, it has become desirable to provide for automated connection of electrical components, such as resistors, capacitors, integrated circuit chips, and chip carriers, to circuit boards. The increasing demands for miniaturization have also further complicated the connection of leads to the components to complete the connection of the components to the circuit boards. Thus, the operation of connecting leads to their circuit elements has been time consuming and has slowed down the process of assembling finished circuit boards ready for use in a particular electrical device.